my initial thoughts are "complete rewrite" lol

secondly even though "google loves wordpress" I personally don't think it will make a blind bit of difference to your stores if it is integrated into a wordpress installation because the underlying content will be exactly the same.
when I first thought about building ANS I did consider wordpress and also drupal. If I was going to port it to anything I would have to say Drupal would be the platform to use.
I have also been looking @ crowd fusion, a new cms which is surely going to become huge soon.. checkout their video here:
http://www.crowdfusion.com/video/